1. Technical Field
The present invention relates generally to a vehicle safety system and, particularly, to a system which provides a driver with views and/or information regarding the area around a vehicle. More particularly, it relates to automatic adjusting of side view mirrors of articulated vehicles such as tractor trailers. In one aspect, the invention contemplates calculating an angle between a tractor and trailer and adjusting the mirrors accordingly. In another aspect, the invention contemplates a transducer bar and control therefor.
2. Description of the Related Art
The maneuvering ability of articulated vehicles such as tractor-trailer combinations is often hampered by the difficulty in quickly and conveniently determining the location of the rear end of the trailer and in viewing the area behind the rear end of the trailer. This is particularly so when the trailer is long and the tractor is turning away from the driver, e.g., toward the right. Typically, externally mounted side mirrors are placed on both sides of the tractor. These mirrors are rigidly positioned for straight ahead driving. Therefore, during turns, one mirror provides a view of the side of the trailer while the other mirror provides a view of the area to the side of the trailer. Neither of these views is useful. The much needed view of the rear of the trailer is not provided.
Although the driver can view the left rear end of the trailer and behind it by looking out the left window when the trailer is turning toward the left, the driver must turn his head and divert his attention away from the front of the vehicle. The driver's peripheral vision may not provide immediate perception of events occurring at the front of the vehicle. Moreover, the driver is unable to peer out the right window and view the right rear end of the trailer during a right turn. Stationary mirrors are also deficient when a tractor-trailer is backing into a loading or unloading area such as a dock during an attempt to park. In these situations, the tractor is almost always at an acute angle relative to the trailer to facilitate docking maneuvers. Stationary mirrors do not permit the rear of the trailer to be viewed during parking as the angle between the tractor and the trailer does not permit such a view. It is often necessary for the driver to leave the vehicle or to obtain the assistance of an additional person to perform the backing and parking maneuvers.
In view of these problems, numerous attempts have been made to provide a mirror which pivots or rotates to provide a view of the rear of a trailer during turns. Some of these prior art systems are disclosed in U.S. Pat. Nos. 2,988,957; 3,469,901; 3,527,528; 3,536,382; 3,749,480; 4,609,265; and 4,632,525. Many of these devices require complex mechanical devices with or without complicated electric circuits to rotate the side mirrors. Some devices are activated only by the turn signal of the vehicle.
In other prior art, tractors become equipped with a transducer bar that has multiple transducers emitting signals towards an attendant trailer. Based upon signals reflected from the trailer, and received by transducers of the transducer bar, an angle between the tractor and trailer is calculated and side-view mirrors or spotlights become adjusted accordingly. With these, however, the adjustment systems utilize mathematically fixed look-up tables (LUT's) optimized for a specific orientation (i.e., fixed length) between the tractor and trailer. LUT's also typically require collecting data from empirical testing which is labor intensive, especially if multiple LUT's are required for multiple tractor-trailer orientations. Some of these systems also require complex algorithms that cross-reference signals received by one transducer with signals received by another transducer.
In addition, transducer bars of the prior art often do not have a symmetrical orientation, which can complicate manufacturing, or they have exact angular orientation between adjacent transducers, which suppresses robustness during tractor-trailer angular computations.
Accordingly, the art of providing vehicular safety systems, especially the adjustment of mirrors or other equipment in accordance with an angle between a tractor and trailer, has need for robustness to accommodate differing tractor-trailer orientations and ease of manufacturing.